Displacement sensors, such as microphones and pressure sensors, are well-known. Many displacement sensors may be based on one or more of electrical capacitance, electrical impedance, or magnetic fields. These electrical and magnetic based displacement sensors may be limited due to one or more of: low sensitivity, the need for high-voltage biasing, poor electrical isolation, environmental factors, and response nonlinearities. These limitations may require a close coupling between transducer design and the sensor mechanical design, which may limit performance and the operational size of the displacement sensor. Optical displacement sensors, such as displacement sensors using an etalon, may be electrically and magnetically insensitive, which may mitigate limitations found in electrical and magnetic based displacement sensors.